1. Field of the Invention
The present invention relates to a skeleton type brushless motor, and particularly, to a skeleton type brushless motor by which a leakage flux is small, and a maneuverability and an efficiency are increased.
2. Description of the Background Art
FIG. 1 is a partially longitudinal sectional view showing a conventional skeleton type brushless motor, and FIGS. 2 and 3 are a side view and an enlarged view showing the conventional skeleton type brushless motor.
FIG. 4 is a side view showing a stator core in the conventional skeleton type brushless motor shown in FIG. 1, and FIGS. 5 and 6 are a side view and a plan view showing a PCB (Printed Circuit Board) cover in the conventional skeleton type brushless motor shown in FIG. 1.
As shown in FIGS. 1, 2, and 3, the conventional skeleton type brushless motor comprises: a rotor 111, a stator 121 in which the rotor 111 is received with an air gap therebetween, a PCB 151 in which a drive control circuit (not shown) for rotating and controlling the rotor 111 is formed; and a PCB cover 153 which is coupled to one side of the stator 121 for receiving and supporting the PCB 151.
The rotor 111 is made by a permanent magnet of cylindrical shape, and a rotational shaft 112 is fixed to a center of the rotor 111 so as to be rotatable as a single body with the rotor 111.
As shown in FIG. 4, the stator 121 comprises: a stator core 123 on which a first rotor receiving part 125a and a second rotor receiving part 125b are formed as a single body, a bobbin 127 which is assembled to the stator core 123, a coil 129 wound around the bobbin 127 and power is applied alternatively to each other.
The stator core 123 includes a first stator core 124a on which the first rotor receiving part 125a and the second rotor receiving part 125b which are disposed facing each other with the rotor 111 therebetween and generates magnetic poles alternatively with each other in accordance with a position of a magnetic pole on the rotor 111 are formed as a single body, and a second stator core 124b fixed to the first stator core 124a penetrating the bobbin 127 for forming a magnetic path.
The first stator core 124a and the second stator core 124b are made by laminating steel sheets and assembled as a single body with each other by rivet 131. In addition, a pair of through holes 133 are formed on the first stator core 124a as penetrating the plate surface thereof.
A pair of detent parts 135, which are symmetric with each other centering around the rotational shaft 112 of the rotor 111, are formed on the respective first rotor receiving part 125a and the second rotor receiving part 125b so that the rotor 111 is not arranged on a position of zero torque for initial driving the rotor 111.
The rotational shaft 112 of the rotor 111 is rotatably supported by a pair of bearings 137, and a bearing housing 139 is coupled around the bearings 137 so as to receive and support the bearings 137.
As shown in FIGS. 1 and 3, a bearing receiving part 141 is formed at center part of the bearing housing 139 so as to receive and support the bearing 137, and an extended receiving part 143 is formed on one side of the bearing receiving part 141 so as to cover exposed part of the rotor 111 which is exposed from the stator core 123 along with the rotational shaft direction.
A screw boss 145 which is received and coupled to the through hole 133 of the first stator core 124a is formed on boundary part of the extended receiving part 143 so that the screw 147 can be coupled via the shaft center.
Meanwhile, as shown in FIG. 5, a sensor receiving part 155 is formed on a center line of the rotor 111 in length direction of the FIG. 5 for receiving and supporting a position sensor (not shown) which detects a rotation position of the rotor 111 as having 90xc2x0 of phase difference from a horizontal center line of the first and second rotor receiving parts 125a and 125b. 
However, in the conventional skeleton type brushless motor, the first rotor receiving part 125a and the second rotor receiving part 125b are formed as a single body with each other, and therefore a leakage flux may be generated through a connected part, and accordingly, an effective magnetic flux is reduced. Therefore, the efficiency of the motor is lowered.
Also, in case that an outer diameter of the rotor 111 is increased in order to increase an output, then a width and a length of the stator 121 should be increased for corresponding to the increased outer diameter of the rotor, and therefore the motor can not be constructed compactly.
In addition, the extended receiving part 143 is formed integrally with the conductive bearing housing 139 for receiving the exposed part of the rotor 111 exposed from the stator core 123, and therefore, an eddy current loss may be generated by the extended receiving part 143.
Also, if the detent part 135 is enlarged so as to get advantage for initial driving, the air gap is enlarged relatively, and therefore the efficiency of the motor is lowered and it is not easy to improve initial maneuverability.
In addition, the position sensor is disposed on a position of 90xc2x0 from the horizontal center line of the first and second rotor receiving part 125a and 125b and detects the rotation position, and therefore a delaying occurs until peak value of applied current is reached due to inductance components, if the magnetic pole of the rotor 111 and the electric current is applied another coil, whereby the efficiency of the motor is lowered.
Also, a DC (Direct Current) electric source should be used in the conventional skeleton type brushless motor, and therefore an additional DC power supplying device must be needed, which results in a large volume and high cost.
Therefore, an object of the present invention is to provide a skeleton type brushless motor which is able to reduce a leakage flux and improve maneuverability and efficiency.
To achieve the object of the present invention, as embodied and broadly described herein, there is provided a skeleton type brushless motor comprising: a rotor in which a rotational shaft is fitted and fixed; a stator including a first stator core and a second stator core in which a rotor receiving part for receiving the rotor is formed respectively, a coil winding unit coupled to the stator cores, and a coil wound on the coil winding unit; and wherein the first and the second stator cores are separated electrically with each other and faces each other centering around the rotational shaft of the rotor.
Also, the rotor receiving part comprises a first rotor receiving part and a second rotor receiving part of semicircular shape. In addition, a first separate space and a second separate space are formed between both ends of the first rotor receiving part and both ends of the second rotor receiving part.
Also, outer surfaces around both ends of the first rotor receiving part and of the second rotor receiving part in the first and second stator cores are protrudingly formed outwardly in a radial direction of the rotor.
Also, a rotation position sensor for sensing a rotational position of the rotor is disposed around 10xc2x0xcx9c20xc2x0 in opposite direction of the rotational direction of the rotor from the separate space nearer to the coil winding unit.
Also, the skeleton type brushless motor according to the present invention comprises a driving control unit coupled to the coil winding unit in the rotational shaft direction for driving and controlling the rotor, and the driving control unit includes a sensor receiving part so that the rotational position sensor can be received therein.
Also, the skeleton type brushless motor further comprises a pair of shaft support parts for supporting the rotational shaft of the rotor so as to be rotatable, and a pair of separating members between the stators for separating the stator and the shaft support part. That separating members respectively includes a shielding member for shielding the separate spaces.
In addition, the skeleton type brushless motor comprises a driving control unit coupled on one side of the coil winding unit in the direction of the rotational shaft of the rotor for driving and controlling the motor, and the driving control unit is a PCB (Printed Circuit Board) on which a drive control circuit is formed. The PCB further comprises an AC capacitor connected to a utility power for decreasing the utility power, and a rectifier circuit for rectifying the power depressed by the AC capacitor.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.